Evaluation of Ciprofloxacin (gyrA, parC Genes) and Tetracycline (tetB Gene) Resistance in Nosocomial Acinetobacter baumannii Infections.

BACKGROUND: Acinetobacter baumannii plays an important role in some types of nosocomial infections as an opportunist microorganism which increases levels of resistance to antibacterial drugs and disinfectants.

OBJECTIVES: The aim of this study was to determine the resistance and sensitivity of A. baumannii to different antibiotics and evaluate the minimal inhibitory concentration (MIC) for Ciprofloxacin and Tetracycline; in addition to Surfanios, Citron and Aniosyme DD1 disinfectants, and also to detect the presence of gyrA, parC and tetB gene bands in the isolates.

MATERIALS AND METHODS: In this study, 65 A. baumannii isolates were collected from the hospitalized patients in NIOC hospital (National Iranian Oil Company hospital) of Tehran, Iran during 2010-2011. The pattern of sensitivity to antibiotics was determined using CSLI disk diffusion and MIC methods. Furthermore, resistance of isolates to the common disinfectants (Surfanios Citron and Aniosyme DD1) was determined in different hospital wards. Presence of gyrA, parC and tetB gene bands was also detected by PCR method.

RESULTS: Frequency of Acinetobacter resistance to Amikacin, Ciprofloxacin, co-Trimoxazole, Ceftazidime and Ceftriaxone was 100% in the isolates reviewed in this study. The frequency of resistance to Gentamicin and Tetracycline were 86.1% in the isolates. The MIC of Ciprofloxacin in all (100%) of isolates was 32-64 μg/mL which showed the resistance to Ciprofloxacin In 86.1% of cases the Gentamicin and Tetracycline MIC were ≥ 16 μg/mL and in 13.9% of isolates the Gentamicin and Tetracycline MIC were 4 μg/mL, these results showed the resistance and sensitivity to the Gentamicin and Tetracycline, respectively. Additionally, all (100%) of the A. baumannii isolates were resistant to disinfectant concentrations, which were used with the methods recommended by manufacturers (0.5%). In 100% of the isolates parC and gyrA genes bands were detected, and tetB gene was also detected in 86.1% of Tetracycline resistant isolates.

CONCLUSIONS: Due to the high resistance of A. baumannii isolates to most antibiotics in our study and also its high resistance to the common disinfectants usually used in hospitals, it seems that more attentions should be paid for applying disinfectants. Since most of the isolates were collected from tracheal and sputum samples (46%), it seems that respiratory tract is the most t prevalent site of infection among Acinetobacter infections. Therefore, disinfecting the respiratory tract related equipment and instruments by using proper disinfectants seems to be an appropriate way to prevent these infections.